Temperature responsive control device

ABSTRACT

A device for controlling the movement of a control member between first and second positions in accordance with a varying temperature condition and a power condition generated by a temperature-power source. The device includes means responsive to the varying temperature condition and the power condition for driving the control member between the first and second positions so that (1) the control member is driven to the first position when no power condition is generated and the temperature condition is below a prescribed level, (2) the control member is driven toward the second position as a function of the temperature condition when the power condition is generated, and (3) the control member is driven to a prescribed intermediate position between the first and second positions when the temperature condition is at or above the prescribed level and the power condition is terminated.

United States Patent [191 Schreiner [451 Feb. 5, 1974 TEMPERATURERESPONSIVE CONTROL DEVICE Inventor:

Louis W. Schreiner, Palatine, 111.

Charles M. Carter, Northbrook, ll]. a part interest Feb. 17, 1971Assignee:

Filed:

Appl. No.:

US. Cl 123/119 F, 60/6, 261/39 B Int. Cl. F02m 1/10, F01b 21/00 Field ofSearch 123/119 F; 60/6, 7; 261/44,

References Cited UNITED STATES PATENTS 7/1930 Gwisdalla 123/119 F 4/1931123/119 F 11/194] ..123/119 F 2,942,596 6/1960 Carlson 123/1 19 F2,946,577 7/1960 Dennison et a1. 123/119 F FOREIGN PATENTS ORAPPLICATIONS 1,223,427 2/1960 France 123/119 F Primary Examiner-WendellE. Burns Attorney, Agent, or Firm-Charles M. Carter [5 7] ABSTRACT Adevice for controlling the movement of a control member between firstand second positions in accordance with a varying temperature conditionand a power condition generated by a temperature-power source. Thedevice includes means responsive to the varying temperature conditionand the power condition for driving the control member between the firstand second positions so that (l) the control member is 10 Claims, 5Drawing Figures PATENTEU FEB INVENTOR LOUIS WSCHREINER BY HTTORN EYTEMPERATURE RESPONSIVE CONTROL DEVICE BACKGROUND OF THE INVENTION Thisinvention pertains to a temperature responsive control device and morespecifically to a power choke for an internal combustion engine.

Various automatic chokes for internal combustion engines are known whichfunction as temperature responsive control devices. However, such chokeshave not provided adequate control for all conditions. Power chokesconstructed in accordance with the present invention provide foradequate control during hot and cold starts.

During cold starts of a choke constructed in accordance with the presentinvention, the butterfly valve is fully closed when the engine cranks.Once the engine fires and carburetor vacuum is developed, the butterflyvalve is opened to a position determined by the engine temperature andthereafter during engine operation the butterfly valve position isdetermined by the engine temperature.

During hot starts, the butterfly valve is maintained in a prescribedopen position when the engine cranks. Once the engine fires andcarburetor vacuum is developed the butterfly valve is again opened to aposition determined by the engine temperature and thereafter thebutterfly valve position is dependent upon the engine temperature.

SUMMARY An object of the present invention is to provide a new andimproved temperature responsive control device for controlling themovement of a control member between first and second positions inaccordance with a temperature condition and a power condition generatedby a temperature-power source so that the control member position isdetermined by the temperature condition when the power condition isgenerated. Another object is to provide such a temperature responsivecontrol device wherein the control member is moved to a prescribedintermediate position when the power condition is terminated while thetemperature condition is at or above a prescribed level.

A further object of the present invention is to provide a new andimproved automatic choke control device for an internal combustionengine. Still another object is to provide such an automatic chokecontrol device wherein, during cold starts, the butterfly valve is fullyclosed while the engine cranks and is opened to an operating positiondetermined by the engine temperature when the engine starts. A furtherobject is to provide such an automatic choke wherein the butterfly valveis moved between the fully closed position and a fully open position inaccordance with the engine temperature during engine operation. Anadditional object'of the present invention is to provide such anautomatic choke control device wherein the butterfly valve is maintainedin a prescribed open position during hot starts. A still further objectof the present invention is to provide such an automatic choke controldevice wherein the temperature operating range is adjustable and the hotstart temperature is presetable.

A further object of the present inventionis to provide a new andimproved automatic choke control device for an internal combustionengine having a carburetor and a choke butterfly valve movable betweenfirst and second positions which includes a housing having an innerchamber associated with the engineso that the temperature in the innerchamber is determined by the engine temperature, a power sourceconnected to the butterfly valve and operable to drive the butterflyvalve between the first and second positions as a function of engineoperation, first means responsive to the temperature in the innerchamber for controlling the operation of the power source so that thebutterfly valve position is determined by the engine temperature, andsecond means responsive to the temperature in the inner chamberattaining a prescribed level and to the butterfly valve attaining aprescribed position for overriding the first means and for preventingthe power source from driving the butterfly valve from the prescribedposition to the first position when engine operation is terminated whilethe temperature in .the inner chamber is at or above the prescribedlevel.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a portion ofan internal combustion engine illustrating the application of an auto- Imatic choke control device constructed in accordance with the teachingsof the present invention;

FIG. 2 is an end elevational view of a first embodiment of an automaticchoke control device constructed in accordance withthe teachings of thepresent invention;

FIG. 3 is aside elevational view of automatic choke control device shownin FIG. 2 taken generally along line 2 2;

FIG. 4 is a fragmentary side elevational view of a portion of theautomatic choke control device shown in FIGS. 2 and 3 which is modifiedto accommodate an air filter; and

FIG. 5 is a cross sectional side elevational view of a second embodimentof an automatic choke control device constructed in accordance with theteachings of the present invention.

DESCRIPTION OF THE INVENTION Referring now to the drawings and morespecifically to FIG. 1, a portion of an internal combustion engine isillustrated which includes a carburetor 10 having an air horn 20, theupper end 12 of which is adapted to be fitted to an air filter and alower end 14 which is connected to an intake manifold 16. The enginealso includes an exhaust manifold 17. A butterfly choke valve 18 ismounted within the air horn 20 for pivotal movement about shaft 19.

In accordance with the present invention, a new and improved automaticchoke control device 22, which is mounted to the exhaust manifold 17, isprovided for controlling the pivotal movement of the butterfly chokevalve 18 between a fully closed position and a fully opened position.The automatic choke control device 22 is connected to the butterflychoke valve by a connecting shaft 24and a linkage 26, as is conventionalwith present automatic choke control devices. Referring now to FIGS. 2and 3, a first embodiment of an automatic choke control device 22constructed in accordance with the teachings of the present invention isillustrated in'greater detail. The exemplary choke control deviceincludes a main housing 40 having an inner chamber 42, an outlet port44and an inlet port 46. The outlet port 44'is connected to the vacuum sideof carburetor 10 via tubing 28 as illustrated in FIG. 1. The

inlet port 46 is connected to a heater tube 30 which passes through theexhaust manifold 17. The choke control device 22 also includes a powersource 48 which is connected to the butterfly choke valve 18 by theconnecting rod 24 and the linkage 26.

In the exemplary arrangement, the power source 48 if in the form of aspring biased diaphragm including a rubber diaphragm member 50, a coilspring 52 and a plunger 54 having a tab 55 secured thereto which isconnected to the connecting rod 24. The inner chamber 56 of the powersource communicates with the inner chamber 42 of the main housing via anair port (or vent) 58 formed in projection 59 of the housing 40 so thatthe diaphragm 50 is drawn downward as viewed in FIGS. 2 and 3 when avacuum is created in the inner chamber 42 by the carburetor. The upperend of the plunger 54 is connected to the top of the diaphragm 50 sothat it moves up and down with the diaphragm and the position of thebutterfly choke valve 18 is determined by the diaphragm position. Whenthe diaphragm 50 and thus the plunger 54 are in the uppermost positionas shown in FIG. 3, the butterfly choke valve 18 will be in a horizontalposition as viewed in FIG. 1 so that the air born is closed. That is,the butterfly choke valve will be in the fully closed position. As thediaphragm 50 is drawn downward as viewed in FIG. 3, the plunger 54 isdrawn downward therewith causing the connecting rod 24 to be drawndownward as viewed in FIG. 1 so that the butterfly choke valve 18 movesto an open position such as that illustrated in FIG. 1. When thediaphragm 50 is drawn to its bottomed or lower-most position, thebutterfly choke valve will be in a vertical position as viewed in FIG. 1and thus will be in the fully opened position. During this fully opencondition, a rubber washer 53 associated with plunger 54 will seat ontop of the projection 59 in which the air port 58 is formed so that theair port is closed off and so that strain on the diaphragm is relievedin the face of maximum carburetor vacuum. The washer seating will alsofunction to shut off any leakage that may occur around the plungerbearing positioned within the projection 59.

In the exemplary arrangement, a spring-loaded valve 60 is positioned inthe inlet port 46 to control the flow of air therethrough. The spring 61is adjusted to balance the force on valve 60 due to the vacuum inchamber 42 and causes the valve 60 to be closed in the absence of suchvacuum so that the inlet port 46 is closed. As will become apparent,vacuum developed in the inner chamber 42 by the carburetor will causethe valve 60 to open under prescribed conditions so that heated air maybe drawn into the inner chamber 42 through the heater tube 30.

In accordance with the present invention, first means are provided forresponding to the temperature in the inner chamber 42 for controllingthe operation of the power source 48 when the engine is operating sothat the butterfly choke valve position is determined by the enginetemperature. Additionally, second means are provided for responding tothe temperature within the inner chamber 42 attaining a prescribed leveland to the butterfly choke valve attaining a prescribed position foroverriding the first means and preventing the power source 48 fromdriving the butterfly choke valve from the prescribed position to thefully closed position when engine operation is terminated and while thetemperature within the inner chamber 42 is at or above the prescribedlevel. In the exemplary arrangement, the first and second means are inthe form of portions of a bi-metallic element 62 which is secured to thehousing 40 at 64. The bi-metallic element 62 is connected to one end ofa control element 66 at 68. The control element 66 is adapted to engagethe valve 60 and is connected to the lower end of the plunger 54 at lips70. The bi-metallic element 62 responds to the temperature within theinner chamber 42 so that the right hand portion 620 as viewed in FIG. 3moves downward as the temperature becomes colder and moves upward as thetemperature becomes warmer. Accordingly, as the temperature within theinner chamber 42 becomes colder the right hand end of the controlelement 66 is drawn downward as viewed in F IG. 3 to allow for openingof the valve 60 responsive to vacuum being developed within the innerchamber 42. Similarly, as the temperature within the inner chamber warmsup, the right hand end of the control element 66 is driven upward by thebi-metallic element 62 to limit or prevent opening of the valve 60. Inlike manner, as viewed in FIG. 3, the left hand portion 62b of thebi-metallic element 62 moves to the left as the temperature within theinner chamber 42 becomes colder and moves to the right as thetemperature becomes warmer. The bimetallic portion 62b is provided witha hook end 72 which is adapted to engage or hook the lower end 70 of theplunger 54 under prescribed hot start conditions so that the plunger isheld by the hook end 72 and is prevented from moving upward as long assuch conditions exist.

At this point, it may be helpful to provide a brief description of theoperation of the automatic choke control device shown in FIGS. 2 and 3as the engine is started and operates. Initially, it will be assumedthat the idle engine is cold so that portions 62a and 62b of thebi-metallic element are in their cold state positions respectivelytoward the bottom of the housing 40 and toward the left hand end of thehousing as viewed in FIG. 3. Under these conditions, the control element66 will have its right hand end positioned toward the bottom of thehousing 40 and the plunger 54 and diaphragm 50 will be in the upperposition as shown in FIG. 3. When the engine is started under theseconditions, the vacuum created by the carburetor causes the valve 60 toopen so that air is drawn into the inner chamber 42 through inlet port46 from the heater tube 30. The air drawn into the inner chamber 42heats up as the engine heats up so that bi-metallic element 62 likewiseheats up. During such heat-up, the portion 62a of the bi-metallicelement moves upward forcing the right hand end of the control element66 upward so that the valve 60 is likewise driven upward toward theclosed position. As the valve 60 begins to close under these conditions,the vacuum begins to build up within the inner chamber 42 and thuswithin the inner chamber 56 of the diaphragm assembly. This causes thediaphragm 50 to be drawn downwardly and thus causes the plunger 54 to becurrently drawn downwardly. Responsive to downward movement of theplunger 54, the butterfly choke valve 18 is opened correspondingly. Asthe plunger 54 moves downward the left hand end of the control element66 is driven downward therewith causing the valve 60 to open. Thediaphragm 50 and the plunger 54 will move downward until the valve 60 isopened sufficiently to equalize the pressure within the inner chambers42 and 56 so that the vacuum force on the diaphragm 50 iscounterbalanced by the force of the spring 52. As the bi-metallicelement 62 becomes progressively hotter responsive to progressivelyhotter air being drawn into the inner chamber 42 the balance point ofthe diaphragm assembly moves progressively lower and thus the butterflychoke valve is opened progressively. Thus it will be apparent that theposition of the butterfly choke valve is determined by the temperatureof the air drawn into the inner chamber 42 and thus is dependent uponthe temperature within the engine exhaust manifold 17.

The portion 62b of the bi-metallic element 62 is provided to allow forhot starts of the engine. This is accomplished by limiting operation ofthe automatic choke control device when the engine is hot (when themanifold temperature is hot) and the bi-metallic element 62 is in itsheated up condition. When the plunger 64 has been drawn downward asufflcient distance and a prescribed temperature condition exists withinthe inner chamber 42 to cause the portion 62b of the bimetallic elementto have moved sufficiently to the right as viewed in FIG. 3, the hookedend 72 of portion 62b will be positioned above the lips 70 of theplunger 54 so that, when the engine is turned off and carburetor vacuumis no longer generated, the plunger is driven upward by the spring 52and the hooked end 72 will engage the lips 70 to hold the plunger in aprescribed intermediate position. Under these conditions, the butterflychoke valve 18 is held in a prescribed intermediate open position ratherthen returning to the fully closed cold start position. It is desireablefor the butterfly choke valve to be maintained in this intermediateposition to allow for starting of a hot engine.

As the engine remains idle over a period of time, the temperature withinthe inner chamber 42 will cool down, representing engine cooling, sothat the bimetallic element portion 62b moves to the left as viewed inFIG. 3. At a prescribed temperature level the portion 62b will havemoved sufficiently to the left to release the plunger 54 so that thediaphragm assembly can return to the cold start condition as illustratedin FIG. 3. At such time, the automatic choke control device is again incondition for a cold engine start and will function as described above.

Further, in accordance with the present invention, means are providedfor adjusting the operating conditions of the automatic choke controldevice. Referring to FIG. 3, a threaded operating adjustment element 74is provided for presetting the proper cold run position of portion 62aof the bi-metallic element 62. That is, element 74 allows for presettingthe bottomed position of portion 62a so that, upon engine starting, adesired vacuum is developed in inner chambers 42 and 56 causing theplunger 54 and thus the butterfly valve 18 to be moved to the desiredcold run position for the engine. Additionally, a cold run limitadjustment threaded element 76 is provided for the purpose of limitingthe cold run position of portion 62 a responsive to adjustment of theoperating adjustment threaded element 74. Without the cold run limitadjustment, in extremely cold conditions, the bi-metal 62a could bepreset so that the butterfly valve would be closed more than desired forcold running conditions causing engine flooding. A hot start adjustmentthreaded control element 78 is provided for presetting the temperatureat which the hooked upper end 72 of portion 62b of the bimetallicelement will be positioned to engage the lips of the plunger 54.

Referring to FIG. 4 a modified portion of the automatic choke controldevice 22 shown in FIGS. 2 and 3 is illustrated. In this modifiedarrangement, the inlet port 46 is adapted to admit air directly from theatmosphere rather than being connected to the manifold heater tube 30 asshown in FIG. I. With this arrangement, an air filter material may beprovided for filtering the air admitted through the inlet 46. With thisarrangement, the engine heat is conducted to the inner chamber 42through the housing 40 which is mounted on the engine, as opposed tohaving hot air drawn into the inner chamber from the manifold heatertube 30. This arrangement is satisfactory as long as sufficientconductive path is provided between the engine and the automatic chokecontrol device.

Referring to FIG. 5, a second embodiment of an automatic choke controldevice 122 constructed in accordance with the teachings of the presentinvention is illustrated. This embodiment is similar to the embodimentshown in FIGS. 2 and 3 with the numbering elements being increased by100. However, port 146 is an outlet port which is connected to thecarburetor vacuum side and no inlet port is provided. Additionally, inthis arrangement, the bi-metallic element is split into two separateelements 162a and 16212. Element l62b functions as did portion 62b ofbi-metallic element 62, whereas element 162a has a reverse action tothat of portion 62a of bi-metallic element 62 so that it moves upward asthe temperature within the inner chamber 142 becomes colder and it movesdownward as the temperature within the inner chamber 142 becomes warmer.Further, spring 161 associated with valve 160 has a reverse action tothat of spring 61 so that the valve 160 is thereby urged open. A smallbleeder port may be provided in the housing to reduce stringentrequirements on the valve 160. Adjusting element 176 allows forpresetting the valve 160 to a prescribed open, cold run position.

For the purpose of clarifying the operational differences between theembodiments of FIGS. 3 and 5, a

brief description of the operation of the automatic.

choke control device 122 will be set forth. In this em bodiment the tab155 of plunger 154 is similarly connected to the butterfly valve 18 sothat the butterfly valve position is dependent upon the position ofplunger 154. During cold start engine conditions, the bi-metallicelement 162a is in its uppermost position as limited by the cold runadjusting element 176 causing the right hand end of the control element166 to be in its uppermost position so that the valve 160 is open to thecold run position. As the engine starts, vacuum is generated in theinner chamber 1142 by the carburetor causing the diaphragm assembly 1148to attain a desired position so that the butterfly choke valve 18attains the desired cold run position. As the engine heats up, the heattherefrom is conducted to the housing causing the temperature in theinner chamber 142 to heat up concurrently therewith. Responsive thereto,the bi metallic element 162a moves downward allowing the spring 161 toforce the valve 160 open further and thus 7 allowing the vacuum withinthe inner housing 142, as well as within chamber 156 of the diaphragmassembly through port 158, to increase. This causes the diaphragm andthe plunger 154 to be drawn downward so that the butterfly valve 18 isopened correspondingly. As the plunger 154 is drawn downward, the righthand end of the control element 166 is pivoted upward causing the valve160 to close correspondingly. The diaphragm assembly will move downwarduntil the valve 160 has been closed sufficiently to adjust the pressurewithin the chamber 156 so that the vacuum force on the diaphragm 150 iscounterbalanced by the spring force of the spring 152. As thebi-rnetallic element 162a becomes progressively hotter responsive toincreased engine temperature, the balance point of the plunger assemblymoves progressively lower and the butterfly choke valve is openedprogressively. Accordingly, the butterfly choke valve position isdetermined by the position of the bi-metallic element 162a which in turnis dependent upon the temperature within the chamber 142 and thus isdependent upon the engine temperature.

The bi-metallic element 162b functions as the bimetallic element 62bdescribed above herein to allow for hot starts and the operation thereofwill therefore not be set forth. Additionally, a hot start adjustmentthreaded element 178 and an operating adjustment threaded element 174have been provided to allow for presetting of the hot start temperatureand presetting of the desired operating conditions for the automaticchoke.

In actual practice, the vacuum produced by the carburetor is reduced bya factor of about 10 to 1 under maximum acceleration. With the exemplaryautomatic choke control devices, the butterfly choke valve will tend toclose under maximum acceleration. The amount of this closure can becontrolled in the design of the exemplary automatic choke controldevices to provide a desired richer fuel mixture for such maximumacceleration. Since in actual practice the vacuum generated drops toabout one pound per square inch during maximum acceleration, thisbecomes a limiting factor around which the exemplary automatic chokecontrol devices must be constructed.

There are conditions under which more driving force is desirable than isattainable if the butterfly valve is allowed to close, such as, ifapositive drive to the fast idle cam of the engine is required. Such apositive drive system has an advantage in that, with such a system, itis not necessary to step on the accelerator before starting to releasethe fast idle cam and to let the choke close, as is now necessary inconventional systems. With the present invention, a version of fast idlecam arrangement can be provided that will allow the choke to close evenif the accelerator is not depressed before starting. However, everyexternal force and friction added to the system degrades the accuracy ofthe choke opening.

There are two ways to allow for use of more driving force which avoidsthe problem of the choke closing too much during acceleration. The firstis to provide a spring-ratchet mechanism on the choke shaft plunger orlinkage 24 that allows the choke only to proceed in the open direction.Any tendency to close due to heavy' acceleration would be checked by theratchet. This ratchet-spring mechanism could be linked to the throttleand disengage whenever the throttle is released so that when the car isstopped the choke can return to the closed position. Another systemwould include a check valve in the vacuum line so that, whenever thevacuum falls below a certain level, the valve closes to retain the highvacuum in the choke drive assembly and the diaphragm so that the chokeis retained in its last high vacuum position. Since such systems do notconstitute a portion of the present invention, they have not beenillustrated herein.

in the exemplary automatic choke control devices, the force generateddue to a given vacuum is constant regardless of the position of thediaphragm assembly. Accordingly, a constant force return spring withinthe diaphragm assembly, while not necessary, may be desirable. In thedisclosed arrangements, the spring force is not constant but isproportional to the linear displacement of the spring. This means thatthe return spring force is proportionally less when the spring is fullyextended. A linear force spring action can readily be obtained by usinga cam spring arrangement on the choke shaft or linkage 24 andeliminating the internal spring. Such a cam arrangement could be used toallow for use of a cable drive system and thus to allow for moreflexibility in the location of the automatic choke control device. Theuse of the spring return on the choke shaft also has an advantage inthat it removes all backlash from the linkage arrangement. Again, thisis not part of the invention and has not been illustrated herein.

I claim:

1. In a device for controlling a desired operation in accordance with avarying temperature condition and a power condition generated by atemperature-power source, the combination which comprises a controlmember movable between first and second positions, and means responsiveto said temperature condition and said power condition for driving thecontrol member between said first and second positions so that (l) thecontrol member is driven to said first position independent of saidtemperature condition when no power condition is generated and saidtemperature condition is below a first prescribed level, (2) the controlmember is moved toward said second position as a direct function of saidtemperature condition when said power condition is generated and whensaid temperature condition is above a second prescribed level, and (3)the control member is moved to an intermediate position between saidfirst and second positions when said temperature condition is at orabove said first prescribed level and said power condition isterminated.

2. In a device for controlling a desired operation in accordance with avarying temperature condition and a power condition generated by atemperaturepower source, the combination which comprises a controlmember movable between first and second positions, drive means connectedto the control member and operable to drive the control member betweensaid first and second positions when said power condition is generated,the drive means including biasing means for driving the control membertoward said first position independent of said temperature conditionwhen no power condition is generated, first control means responsive tosaid temperature condition for overcoming said biasing means andcontrolling the operation of the drive means so that the control memberis driven from said first position toward said second position as adirect function of said temperature condition when said power conditionis generated and when said temperature condition is above a firstprescribed level, and second control means responsive to saidtemperature condition attaining or exceeding a second prescribed level.

and to the control member being within a prescribed range between saidfirst and second positions for overriding the biasing means when saidpower condition is terminated and preventing the biasing means fromdriving the control member to the first position during the existence ofsaid temperature condition at or above said second prescribed level.

3. The control device of claim 2 wherein adjustable means are providedfor pre-setting the temperature condition operating range of said firstcontrol means.

4. The control device of claim 2 wherein adjustable means are providedfor pre-setting said prescribed level temperature condition at which thesecond control means overrides the biasing means.

5. The control device of claim 2 wherein a main housing is providedhaving an inner chamber and an outlet communicating with the innerchamber and being associated with said temperature source so that thetemperature in the inner chamber is determined by said temperaturecondition generated by said tempera- I ture source, wherein the firstand second control means are located within said housing and aredirectly responsive to the inner chamber temperature, and wherein thedrive means includes a spring biased diaphragm device associated withthe inner chamber and a source of vacuum connected to the outlet.

6. The control device of claim 5 wherein the first and second controlmeans include bi-metallic elements mounted within the inner chamber.

7. In an automatic choke control device for an internal combustionengine having a carburetor and a choke butterfly valve movable betweenfirst and second positions, the combination which comprises a housinghaving an inner chamber associated with the engine so that thetemperature in the inner chamber is determined by the enginetemperature, a drive system connected to the choke valve and operable todrive the choke valve between said first and second positions, the drivesystem including means for biasing the choke valve toward said firstposition when the engine is not operating, first means responsive to thetemperature in the inner chamber for controlling the operation of thedrive system so that the choke valve is driven from said first positiontoward said second position as a function of said temperature when theengine is operational, and second means responsive to the temperature inthe inner chamber attaining a prescribed level and to the choke valveattaining a prescribed position for overriding the drive system biasingmeans when engine operation is terminated and preventing the drivesystem from driving the choke valve from the prescribed position to thefirst position during the existence of said prescribed level temperaturewithin the inner chamber.

8. The control device of claim 7 wherein adjustable means are providedfor pre-setting the temperature operating range of said first means.

9. The control device of claim 7 wherein adjustable means are providedfor pre-setting said prescribed temperature at which the second meansoverrides the power source biasing action.

10. The control device of claim 7 wherein the housing includes an outletcommunicating with the inner chamber which is connected to thecarburetor and the carburetor provides a source of vacuum, wherein thedrive system includes a spring biased, movable diaphragm connected tothe choke valve which communicates with the inner chamber and the vacuumcreated by the carburetor, the diaphragm biasing the choke valve to thefirst position when carburetor vacuum is not provided, wherein the firstmeans includes a bimetallic element mounted within the inner chamberwhich controls the vacuum created in the inner chamber by the carburetorin accordance with the inner chamber temperature whereby the diaphragmis moved to a position determined by the existing temperature level inthe inner chamber, and wherein the second means includes a bi-metallicelement mounted within the inner chamber which overrides the springbiasing of the diaphragm and retains the choke valve in the prescribedposition during existence of said prescribed level temperature withinthe inner chamber when carburetor vacuum is not provided.

1. In a device for controlling a desired operation in accordance with avarying temperature condition and a power condition generated by atemperature-power source, the combination which comprises a controlmember movable between first and second positions, and means responsiveto said temperature condition and said power condition for driving thecontrol member between said first and second positions so that (1) thecontrol member is driven to said first position independent of saidtemperature condition when no power condition is generated and saidtemperature condition is below a first prescribed level, (2) the controlmember is moved toward said second position as a direct function of saidtemperature condition when said power condition is generated and whensaid temperature condition is above a second prescribed level, and (3)the control member is moved to an intermediate position between saidfirst and second positions when said temperature condition is at orabove said first prescribed level and said power condition isterminated.
 2. In a device for controlling a desired operation inaccordance with a varying temperature condition and a power conditiongenerated by a temperature-poweR source, the combination which comprisesa control member movable between first and second positions, drive meansconnected to the control member and operable to drive the control memberbetween said first and second positions when said power condition isgenerated, the drive means including biasing means for driving thecontrol member toward said first position independent of saidtemperature condition when no power condition is generated, firstcontrol means responsive to said temperature condition for overcomingsaid biasing means and controlling the operation of the drive means sothat the control member is driven from said first position toward saidsecond position as a direct function of said temperature condition whensaid power condition is generated and when said temperature condition isabove a first prescribed level, and second control means responsive tosaid temperature condition attaining or exceeding a second prescribedlevel and to the control member being within a prescribed range betweensaid first and second positions for overriding the biasing means whensaid power condition is terminated and preventing the biasing means fromdriving the control member to the first position during the existence ofsaid temperature condition at or above said second prescribed level. 3.The control device of claim 2 wherein adjustable means are provided forpre-setting the temperature condition operating range of said firstcontrol means.
 4. The control device of claim 2 wherein adjustable meansare provided for pre-setting said prescribed level temperature conditionat which the second control means overrides the biasing means.
 5. Thecontrol device of claim 2 wherein a main housing is provided having aninner chamber and an outlet communicating with the inner chamber andbeing associated with said temperature source so that the temperature inthe inner chamber is determined by said temperature condition generatedby said temperature source, wherein the first and second control meansare located within said housing and are directly responsive to the innerchamber temperature, and wherein the drive means includes a springbiased diaphragm device associated with the inner chamber and a sourceof vacuum connected to the outlet.
 6. The control device of claim 5wherein the first and second control means include bi-metallic elementsmounted within the inner chamber.
 7. In an automatic choke controldevice for an internal combustion engine having a carburetor and a chokebutterfly valve movable between first and second positions, thecombination which comprises a housing having an inner chamber associatedwith the engine so that the temperature in the inner chamber isdetermined by the engine temperature, a drive system connected to thechoke valve and operable to drive the choke valve between said first andsecond positions, the drive system including means for biasing the chokevalve toward said first position when the engine is not operating, firstmeans responsive to the temperature in the inner chamber for controllingthe operation of the drive system so that the choke valve is driven fromsaid first position toward said second position as a function of saidtemperature when the engine is operational, and second means responsiveto the temperature in the inner chamber attaining a prescribed level andto the choke valve attaining a prescribed position for overriding thedrive system biasing means when engine operation is terminated andpreventing the drive system from driving the choke valve from theprescribed position to the first position during the existence of saidprescribed level temperature within the inner chamber.
 8. The controldevice of claim 7 wherein adjustable means are provided for pre-settingthe temperature operating range of said first means.
 9. The controldevice of claim 7 wherein adjustable means are provided for pre-settingsaid prescribed temperature at which the second means overrides thepower source biasing action.
 10. The Control device of claim 7 whereinthe housing includes an outlet communicating with the inner chamberwhich is connected to the carburetor and the carburetor provides asource of vacuum, wherein the drive system includes a spring biased,movable diaphragm connected to the choke valve which communicates withthe inner chamber and the vacuum created by the carburetor, thediaphragm biasing the choke valve to the first position when carburetorvacuum is not provided, wherein the first means includes a bi-metallicelement mounted within the inner chamber which controls the vacuumcreated in the inner chamber by the carburetor in accordance with theinner chamber temperature whereby the diaphragm is moved to a positiondetermined by the existing temperature level in the inner chamber, andwherein the second means includes a bi-metallic element mounted withinthe inner chamber which overrides the spring biasing of the diaphragmand retains the choke valve in the prescribed position during existenceof said prescribed level temperature within the inner chamber whencarburetor vacuum is not provided.